DESCRIPTION: (Adapted From The Investigator s Abstract): At present a coherent account of speech motor development is lacking. This constitutes a major roadblock to our efforts to assess the potential impact of motor deficits on the development of speech disorders. If the normal course of speech motor development is unknown, atypical developmental patterns cannot be identified. Using newly available technologies, the overall goal of the present project is to implement a multi-leveled and integrative approach to the problem of speech motor development. Speech and basic oral motor functions will be assessed through multiple analytic windows, including direct recording of speech movements, measurement of speech acoustic events, assessment of oral-motor reflexes, and indices of craniofacial anatomy. A long-term objective of this project is to obtain maturational profiles of speech, anatomical, and reflex measures based on tests of large numbers of subjects aged 4 yrs to young adult. Using this method, the maturation of components of the oral motor system can be mapped out. The reflex and anatomic measures provide indices of the biological substrate from which speech motor processes must emerge. We will be able to determine the time of maturation to adult values of both speech-related variables and those reflecting basic oral physiology. The trajectories of these growth curves will be used to test hypotheses about the dynamic interactions of factors related to the acquisition of speech motor skills. In addition, a set of studies of smaller groups of subjects aged 4 to 12 yrs will provide finer grained analyses of speech movement organization. These studies are designed to test the hypothesis that young children are not simply smaller, less skilled performers using the same organizational strategies as adults. Rather children are using distinctive strategies that reflect the different biological tools that they bring to the task of speaking.